1. Field of the Invention
The present invention is directed generally toward agricultural planters and more particularly to a suspension system for such planters.
2. Description of the Related Art
It is well recognized that proper and uniform spacing of seed in the furrow is essential to maximizing crop yield. Recent advances in metering technology have resulted in seed meters capable of singulating seed extremely well on test stands prior to planting. While the advances in metering technology has resulted in improved seed singulation in the field, the same singulation performance achieved on a test stand, is generally not obtainable under field conditions, particularly when traveling at faster planting speeds. For example, although many meters are capable of singulating at 99% accuracy or greater on the test stand, when operating in the field, the same meter may only plant at 95% singulation accuracy. The loss in accuracy under field conditions is due to a number of factors, including changes in vertical motion and vertical acceleration of the planter from jostling, sudden jolts and bouncing of the planter as the planter encounters changes in field topography, ruts, ridges, rocks and other obstacles as the planter traverses the field.
For example, as the planter travels through the field, changes in levelness of the soil and roughness of the field may cause the entire planter and/or the individual row units to bounce and undergo vertical acceleration. With conventional planter row units, the metering system is rigidly mounted to the row unit frame, thereby causing the seed meter to experience the similar bouncing motions and vertical acceleration changes as the planter frame to which it is rigidly mounted.
Subjecting the seed meter to abrupt changes in vertical position or vertical acceleration can effect the uniformity of seed spacing in the furrow by causing variations in the seeds initial vertical velocity upon discharge from the seed meter. It should be appreciated that if seeds fall at different velocities through the seed tube, the spacing between adjacent seeds will be effected. For example, when the seed meter is traveling upward (relative to the global coordinate system) as a seed is being released from the seed selection mechanism, the seed's initial vertical velocity (with respect to ground) will be less than the initial velocity of a seed released when the meter is stationary or traveling downward. This difference in initial vertical velocity will result in a difference in the amount of time required for the seed to fall through the seed tube and into the furrow, which, accordingly, will result in deviations in seed spacing in the furrow. Additionally, sudden jolts or vertical acceleration of the seed meter may result in seeds being dislodged from the seed selection mechanism of the seed meter (i.e., a finger, cavity disk, vacuum disk, etc.) thereby resulting in seed skips, further contributing to seed spacing irregularities.
Planter improvements such as the walking beam gauge wheel depth control have helped to reduce row unit jostling and bounce as the planter traverses the field, however, there remains a need to further reduce the amount of vertical acceleration experienced by the seed meter and to minimize variations in initial vertical velocity between seeds upon discharge from the seed meter.